Active carbon filter factory shares: why the specific surface area of activated carbon is large but the formaldehyde removal effect is average

When customizing the formaldehyde removal air filter, a customer often asks about the formaldehyde removal by activated carbon: Why do some activated carbon have large specific surface area, high CTC and iodine adsorption values, but poor adsorption performance for formaldehyde, ammonia, acetaldehyde and other gases in cigarettes. Please refer to the following activated carbon filter factory to share why the specific surface area of activated carbon is large but the formaldehyde removal effect is average.

Generally, we think that activated carbon adsorbs formaldehyde. The physical adsorption performance of activated carbon has a great relationship with the specific surface area and the micropore size of activated carbon. If the micropore size of the activated carbon is close to the diameter of a certain gas, then its adsorption capacity for this gas is very strong, and it is not easy to desorb after adsorption. However, for gases such as formaldehyde, acetaldehyde and ammonia, due to their low boiling point and less obvious polarity, micropores of specific size should be added to adsorb them, but this technology is difficult to control. Therefore, the physical adsorption of activated carbon on formaldehyde and other gases is not always ideal. Especially when it coexists with other gases, the activated carbon preferentially adsorbs other gases that are better adsorbed, while it rarely adsorbs formaldehyde, etc., and it is easier to desorb. Once desorbed, it will cause secondary pollution.

Therefore, the adsorption of organic gases such as formaldehyde has no very important relationship with the specific surface area. For Henkaes activated carbon filter factory, the principle of chemical adsorption is often used to modify it. Commonly, the activated carbon can be loaded with chemicals or catalysts, or modified by chemical process conditions. It can completely decompose gas and convert it into formic acid, thus avoiding secondary pollution.

Appropriate and good activated carbon additives and modification methods can improve the adsorption efficiency of activated carbon for specific gases by several to dozens of times.